Hello,
It's not a correct thing to have two dates of the same type within the same validity, if you wish you can create new date types to store different dates or create a new record with new validity period of IT0041 and change the data of the data type in question while keeping history.
But I guess you'll never be able to store the same data type twice per single IT0041 record, in order to be able to help you more please share your business scenario.
Hope that helps,
For further clarification, please contact.
Thanks and regards,
Sally